Process of preparing thiophosphates

ABSTRACT

WHERE X is 0 or S, R is a hydrocarbon or a substituted hydrocarbon group such as alkyl, aryl, cycloalkyl, alkaryl, aralkyl, etc., and R&#39;&#39; is a 3-thione-propene-1 or a substituted 3thione-propene-1 group; the preparation thereof by reacting 1,2dithiolium compound with a phosphite ester; the reversion to the original dithionium compound is effected by reacting the thiophosphate under acid conditions; and the uses of such thiophosphates as corrosion inhibitors in acid systems.   Thiophosphates of the formula

Unite States Oude Alink atent [191 Jan. 7, 1975 PROCESS OF PREPARING [21] Appl. No.: 375,056

Related U.S. Application Data [62] Division of Ser. No. l65,336, July 22, 1971.

[52] U.S. Cl 260/970, 252/8.5 C, 252/80, 252/175, 252/389 A, 260/290 R, 260/327 R, 260/947 [51] Int. Cl. C07f 9/16, C02b 5/06 [58] Field of Search 260/970 Primary Examiner-Anton H. Sutto Attorney, Agent, or Firm-Sidney B. Ring; Hyman F. Glass [57] ABSTRACT Thiophosphates of the formula X Rxni -s R where X is 0 or S, R is a hydrocarbon or a substituted hydrocarbon group such as alkyl, aryl, cycloalkyl, alkaryl, aralkyl, etc., and R is a 3-thione-propene-l or a substituted 3-thione-propene-l group; the preparation I thereof by reacting l,2-dithiolium compound with a phosphite ester; the reversion to the original dithionium compound is effected by reacting the thiophosphate under acid conditions; and the uses of such thiophosphates as corrosion inhibitors in acid systems.

4 Claims, No Drawings pounds, and methods for their preparation, are disclosed in THE CHEMISTRY OF HETEROCYCLIC COMPOUNDS, Multi-Sulfur and Sulfur and Oxygen Five-and Six-Membered Heterocycles," PART 1, pages 352-366, by David S. Breslow'et al., Interscience Publishers, 1966.

1,2-dithiole-3-thiones may be expressed by the formula:

where R'and R are substituted groups, for example, alkyl, aryl, cycloalkyl, alkenyl, alkynyl, alkaryl, aralkyl, heterocyclic, etc. In addition, one of the above Rs may be hydrogen. Examples of a wide variety of 1,2- dithiole-3-thiones are presented in the above ,textby Breslow et al in Table 4, pages 352 366, which is incorporated into this application as if part hereof.

l,2-dithiole-3-thiones are conveniently prepared by the classic method of reacting an olefinwith. sulfur, for

1 example, according to the following equation:

The olefin employed in the reaction contains 1. a reactive double bond 2. a primary carbon atom 3. at least four hydrogen atoms on the 3 terminal carbons with at least one hydrogen on the carbon beta to primary carbon atom.

This reaction is carried out at any suitable temperature and time, for example, at about 100 to 300C., such as from about 140 to 240C. but preferably from about 160 to 220C. for a period of about 2 to 160 hours, and about 10 to 50 hours, but preferably about 15 to 40 hours.

The following examples are presented by way of illustration and not of limitation to show the preparation of 1,2-dithiole-3-thiones which may be employed as starting materials to prepare the dithiolium compounds of this invention.

EXAMPLE 1A THE PREPARATION OF 4-PI-IENYL-l ,2-DITHIOLE3-THIONE In a suitable reactor equipped with a stirrer, thermometer and a reflux condenser, was placed 1 l8 g of methyl-styrene and 48 g of sulfur. The mixture was heated for 37 hours at 200210C. After the reaction was completed, the mixture was slowly cooled to room temperature. The product was collected and crystallized from benzene, red crystals, (32 grams, 50% yield), m.p. l22-l24C.

EXAMPLE 2A PREPARATION OF 4-( 3-METI-IOXY-4-HYDROXY)PHENYL- l ,2- DITI-IIOLE-3-TI-IIONE In a suitable reactor equipped with a stirrer, thermometer, addition funnel and reflux condenser was placed 32 g'of sulfur, 1.0 g of di-o-tolylguanidine as catalyst and cc of mesitylene as solvent. The mixture was brought to a reflux (C.) and over a 1 hour period 66 g of isoeugenol was addeddropwise. Reflux was continued for 48 more hours." The mesitylene was decanted from the solid. The solidwas treated twice with 500cc portion of a 5% aqueous potassium hydroxide solution. Upon acidification the product precipitated as a brown solid.

EXAMPLE 3A PREPARATION OF 4-NEOPENTYL-5-T-BUTYL-l ,2-DITI-IIOLE-3 TI-IIONE To a mixture of 320 of sulfur and 6.0 g of di-otolylguanidine was added over a 9 hour period, at a reaction temperature of 210-2l5C., 336 g of triisobutylene, mainly canteen;

EXAMPLE 4A PREPARATION or 4,5-TETRAMETHYLENE-1,2-DIT1-IIOLE-3- THIONE In a suitable reactor equipped with a stirrer, reflux' condenser, thermometer and addition funnel was placed 24 g of sulfur, 171 g of carbon disulfide and 150 The radicaliindicat ed replaces the I-ls in the 4th and/or 5th positions as indicated.

TABLE I cu; cm

CIT:

41) 4-(2-Thienyl-) 42) 5-(2-Thienyl-) Y 4-(4-CH -2-thi6ny1-.) 44 5-(5-CH -2-thienyl-) 144 41151-56311, 145 4-11s-5- -c11,oc,11,-) 146) 4-c11,s-5-c,11,

7 not subject to further oxidative decomposition. There- 1,2-thiole-3-thiones canbe converted to 1,2- dithiolium compounds by oxidizing l,2-dithiole-3- thiones. Any convenient method of oxidation can be employed.

The preferred method of preparation depends on the particular thione to be oxidized. For example, where the thione yields an unstable dithiolium compound, it is desirable to precipitate the dithiolium salt from solution so that it does not decompose. This is done by precipitating the thiolium as an insoluble salt so it will not be decomposed by further oxidation. For example, aryl thiones when converted to the corresponding dithiolium compounds are unstable to further oxidation but their decomposition can be prevented by precipitation from solution during oxidation as insoluble salts.

My Application Ser. No. 79,709, filed Jan. 9, 1970,

discloses that non-aryl substituted such as aliphatic dithiolethiones when converted to the corresponding dithiolium compounds yield stable compoundswhich are fore, it is not as important to precipitate such dithiolium compounds from solution as insoluble salts.

Application Ser. No. 79,709 further discloses that, in

generahthe aliphatic dithiolium compounds are also more water soluble than the aryl dithiolium compounds; For example, certainaliphatic dithiolium compounds are at least 75 percent water soluble in contrast to the less than 10 percent solubility of the aryl dithiolium compounds. Thus aliphatic dithiolium compounds are not only more soluble but are also more stable than the aryl compounds. a

Application Ser. No. 79,709 furth'er discloses that because of their high aqueous solubility and stability the aliphatic dithiolium compounds are particularlyuseful as corrosion inhibitors in aqueous and/or aerated and- /or acidic systems. v

A wide variety of oxidizing agents can be employed, as illustrated by the following:

1. aqueous solution of hydrogen peroxide 2. hydrogen peroxide and an organic or inorganic acid barium permanganate t-butyl-hydroperoxide m-chloroperbenzoic acid Caros acid Peracetic acid Potassium persulfate chromic anhydride l0. perchloric acid, etc. 11. other oxidation agents can also be employed. The choice of oxidizing agent will depend on the particular thione to be oxidized, economics, etc.

In' general, the thione is oxidized :in a suitable solvent I at as low a temperature consistent with a reasonable re- In practice reaction times of from 0.5 hours to 24 or more hours are employed; with hydrogen peroxides shorter time can be employed such as from about 1-2 I hours. With milder oxidizing agents such as organic peroxides longer times may be employed such as 24 .hours with chloroperbenzoic acid.

Any solvent that does not interfer with the reactants and products can be employed for example; water, methanol, ethanol, l-propanol, butanol, acetone, dimethyl sulfamide, dimethyl formamide, ether tetrahydrofuran, chloroform, carbon tetrachloride, etc.

In general, room temperature or lower is preferably employed to reduce side reactions. Higher temperatures may b'e'e mployed' in oxidizing certainthion'e's such as about 50C. or higher in certain instances.

Although Ser. No. 79,709 discloses the oxidation of thiones, dithiolium compounds canbe prepared by other methods such as for example by those described in Advances in Heterocyclic Chemistry," Katritzby, et al., Vol. 7, 1966, published by Academic Press, pp 39-151, which is incorporated herein as if part thereof.

The following Examples are presented by way of illustration and not of limitation.

EXAMPLE 1B 3-t-Butyl-4-neopentyl-1,Z-dithiolium hydrogen sulfate In a 2 liter four necked round-bottom flask equipped with a mechanical stirrer, a thermometer, a reflux condenser and an addition funnel was placed a mixture of 260 grams of 4-neopentyl-5-t-butyl-1 ,2-dithiole-3- thione and 500 cc of glacial acetic acid. The mixture was cooled to 15C. and 258 grams of 30% hydrogen peroxide was added at such a rate that a reaction temperature of 15-25C. was maintained (2 hours). After the addition was completed, the mixture was stirred for an additional 2 hours at room temperature. The solvents were distilled off under diminished pressure. The remaining solid was washed with acetone and filtered to yield 258 grams (80% theory) of 3-t-butyl-4- neopentyl-1,2-dithiolium hydrogen sulfate as a light yellow solid, mp. 189190C; u.v. AMI? (E) 254 mp. (5,000) and 306 mp. (6,800); nmr (solvent D T111 ppm, internal standard t.m.s., 0.03 (s., 1H), 6.74 (s., 2H), 8.22 (s., 9H) and 8.88 (s., 9H). Anal. Calced. for C, H O S C, 44.14; H, 6.74; S, 29.43 Found:

C, 43.98; H, 6.82; S, 29.8

EXAMPLE 2B 3-t-Butyl-4-neopentyl-l ,2-dithiolium perchlorate HSO, C

To a solution of 5 grams of 3-t-butyl-4-neopentyl-l ,2- dithiolium hydrogen sulfate in 5 grams of distilled water was added 4 cc of 70% perchloric acid; The white solid which precipitated was filtered and dried to yield 5 grams (100%) of material,'m.p. 157l58C; u.v. It (E) 254 mp. (4,780) and 307 mp. (5,010). Anal. Calced. for C 2H21S2Cl0 S, 19.5 Found:

EXAMPLE 38 I 3-t-Butyl-4-neopentyl-l,Z-dithiolium hydrogen sulfate The product was prepared in 80% of the'theoretical yield according to a procedure identical as in Example 18, with the exception that instead of-acetic acid as the solvent, a mixture of 50 g of acetic acid and 450 g of isopropanol as the solvent was employed.

EXAMPLE 48 I 3-t-Butyl-4-neopentyl-1,2-dithiolium hydrogen sulfate To a sample of 5.2 grams of 4-neopentyl-5-t-butyl- 1,2-dithiole-3-thione dissolved in 100 grams of chloro-- form was added a solution of 12.2 grams of mchloroperbenzoic acid (85%) in 200 grams of chloroform. The mixture was allowed to stand for 24 hours at 7 room temperature. The chloroform solution was evap-. a

orated under diminished pressure and the remaining solid extracted with 100 cc of distilled water. The aqueous solution was distilled under diminished pressure to yield 4.8 grams(73% of theory) of Example 18.

EXAMPLE 5B 4-Phenyl-1,2-dithiolium hydrogen sulfate This product was prepared in 80% yield from 4- phenyl-l,2-dithiole-3-thione according to the procedure described in Example 4B. Bright yellow solid mp. w My. 1 242 m (15,400) and 345 my. (1,700),nmr (solvent D 0) in ppm, internal standard t.m.s., 0.06 (s., 2H) and 2.05-2.51 (m., 5H).

Anal. Calced. for C -H O S C, 39.1; H, 2.9;.S, 34.8 Found:

' C, 38.8; H, 3.1; S, 34.9

EXAMPLE 6B 3-(p-methoxy phenyl) 1,2 thiolium hydrogen sulfate The desired product was obtained in a 40% yield, according to the procedure described in Example 18, as an orange solid, mp. 195l96C. (dec.), after crystallization from ethanol; u.v. 8, 2 244mu (7,100) aid' t'fi' Anal. CalCed. fOl C oH oO5S3:

C, 39.2; H, 3.3; S, 31.4

Found:

C, 39.1;H, 3.1;S,3l.2 The forrnulae of the above dithiolium compounds are presented in the following Table.

TABLE II R- II 5 The reaction may be summarized as follows:

The anion employed will depend on the properties desired for example solubility, insolubility, partial solubility. Example of anions include sulfates,'bisulfates, sulfites, bisulfites, halides, i.e Cl, Br, I, F, etc., phosphates, phosphites, etc., chlorates, etc. In addition to employing the salts, quaternaries can be employed so that the hydrogen in the positionR is for example alkyl, aryl, etc.

where Ris alkyl such as methyl, etc., and R is hydrogen, alkyl, etc., for example, methyl p-toluene sulfonates, 5. Alkyl phosphates, e.g. (MeO) PO, (EtO) PO, etc. It is to be noted that where the anion is polyfunctional, such as difunctional, 2 moles of the dithiolium would be coupled with one mole of the anion, for example thiourea, etc.

such as where X is sulfate, a dicarboxylic acid such as phthalic acid, etc., for example 10 Pqlyfunctional quaternaries may also be formed, for

example Ilt' lit such as where A is alkylene,

I have now discovered aprocess of reacting the dithiolium compounds described'hereiin with phosphite esters under. basic'conditions to form thiophosphates of the formula where X is O or S, R is a hydrocarbon or a substituted hydrocarbon group such as alkyl, aryl, cycloalkyl, aralkyl, alkaryl, etc., andR is a 3-thi0ne-propene-l or a substituted 3-thione-pr0pene-l groupl have also discovered that the process can be reversed to the original dithionium compound by reacting the thiophosphate product under acid conditions.

The overall reaction can be summarized by the following equations where Bv is a' base. In the following equations the phosphite ester canalso be a thiophosph- I ite, or a mixed oxygenthiophosphite, i.e

l HI (XR);

where X is O or 8. Thus all X's may be oxygen or sulfur or both oxygen and sulfur. Corresponding thiophosphates will be formed,

and/or The formation of IV, V, VI and VII will depend upon B2 A (I /m the nature of R R and R groups and of the phosphite S--P used.

and/or F The dithiolium compounds described herein as well I 5 as others can be reacted. under basic conditions with phosphites to form the monothiophosphates. R40 0R4 In general the reaction is carried out by reacting one v1 v11 mole of the dithiolium compound with at least I mole of phosphite at ambient temperature. such as from about -l0 to 60C, but preferably at about room temperature, i.e., from 0 to about 30C.

The phosphites employed in this invention are of the formula (ROhl H where R is an alcohol moiety, for example, alkyl, aryl,

cycloalkyl, aralkyl, alkaryl, and substituted derivatives I v thereof, but preferably where R is alkyl, for example,

i I a 1 a The reversed reaction is given by the equation: f g oclhlgher and most preferab y lower alkyl In addition, the oxygen phosphites, corresponding thiophosphitev or mixed oxygenthiophosphites can be employed, for example, of the general formula x taxhl n where X is oxygen or sulfur, for example,

R1 R; I v

m I i n l n, Ro'nlnr, (Rsm H, (RSMPH, etc.

Any basic material capable of promoting the reaction can be employed. These include alkali metal and alkaline earth metal hydroxides, oxides, alkoxides, and also salts of these metals with weak, inorganic and organic acids, for example, those derived from Group IA and A of the periodic table.

As examples of the alkali metal and alkaline earth metal hydroxides, there may be mentioned sodium hydroxide, potassium hydroxide, lithium hydroxide, cal- The products obtained are lV and/or V and/or Vl cium hydroxide, barium hydroxide, strontium y d/ V11, ide, and magnesium hydroxide. The alkoxtdes are rep- Since the starting material can be represented by the s s by P and F corresponding two extreme resonance Structures: potassium lithium, calcium, strontium, barium and magnesium alcoholates;

The preferred basic material comprises amines. Al-

though a wide variety of amines can be employed such R2 f as primary, secondary, tertiary, mono and polyamines, RF 4 R3 R1 4 Ra in order to reduce side reactions tertiary amines are l 3 and a employed, preferably volatile tertiary monoammes that S ,1, can be easily removed on completion of the reaction, 1 2 1 for example tertiary amines of .the formula 65 two different phosphor-sulfur bonds can be formed if R, R and since each product formed can exist as R i R two isomers a total of four products is possible.

where the Rs, which may be the same or different, are hydrocarbon, preferably alkyl and most preferably lower alkyl, for example, where the Rs are methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, etc., where the alkyls are straight chained, branched, etc.

Ammonia can also be employed, i.e., where the Rs are hydrogen.

In general, sufficient base is employed to remove the anion so as to render the systems basic, i.e., at least one equivalent of base per mole of dithiolium compound.

The anion X may be stated herein in relation to the dithiolium compound, for example halides (Cl, Br, I, F) chlorates, carboxylates, such as derived from aliphatic acids, for example acetates, propionate's, etc., aromatic acids, for example benzoates, salicylates, phthalates, etc., phosphates, sulfates, sulfonates, etc. i

The thiophosphate can be reconverted to the dithiolium compound byadding-a sufficient amount of an acidic material to render it acidic, thus reverting it to the cationic form. To achieve this at least one equivalent of acid isadded per mole of dithiole. The acidic material can be organic or inorganic, for example, hydrohalic acids such as HCl, HBr, etc., sulfuric, phosphoric, sulfonic acids, etc.; organic acids such as the alkyl, aryl, cycloalkyl, alkaryl, aralkyl, heterocyclic, etc., carboxylic acids, for example acetic, proprionic, butyric, etc., fatty acids such as stearic, oleic, palmitic, etc., acids, benzoic, phthalic, etc., acids.

The following examples are presented for illustration and not limitation.

EXAMPLE 1C To a mixture of 16.4 grams of 3-tertiary-butyl-4- neopentyl-l,2 dithiolium perchlorate (Ex. 28) and 19.0 grams of the dimethylphosphite was added 7.3 grams of triethylamine. After the addition of triethylamine was completed, there was added 100cc of ether and 50 cc of water. The etheral layer was separated and washed several times with water. After the ether solution wasdried over anhydrous magnesium sulfate, the ether was distilled off under diminished pressure. There was isolated 16.5 grams (97% of .theory) of 0,0'- dirnethyl-S-( 2-neopentyl-4 ,4-dimethyl-3 -thionepentene-l) monothiophosphate as a red-purple solid, melting point 6971C; n.m.r. solvent CCh), 1' in ppm, 4.13, 1 H doublet (J 9 cps, vinyl); 6.31, 6 H doublet (J 13 cps, methoxy); 7.66, 2 H singlet (CH neopentyl); 8.63, 9 H singlet (t-butyl), and 9.08, 9 H singlet (t-butyl).

Anal. Calculated for C H O PS Found: I

.EXAMPLE'ZC 0,0'-Dimethyl-S-(2-Neopentyl-4,4-dimethyl-3-thionepentene-l )monothiophosphate A mixture of grams of 3-tertiary-butyl-4- neopentyl-l,2 dithiolium hydrogen sulfate (Ex. 13)

and 15 grams of dimethyl phosphite dissolved in'50 grams of water was treated slowly with 10 grams of purposes of 29% ammoniumhydroxide solution. The product which precipitated was filtered off and washed with water. After drying in vacuo, there was isolated 13.5

14 grams of 0,0'-dimethyl-s-(2-neopentyl-4,4-dimethyl- B-thione-pentene-l) 'monothiophosphate (86% of theory) in all respects identical to the product isolated as described in Example 1C.

EXAMPLE 3C 0,0'-Diethyl-S-( 2-Neopentyl-4,4-dimethyl3-thionepentene-1 monothiophosphate A mixture of 6.0 grams of 3-tertiarybutyl-4- neopentyl-1,2 dithiolium perchlorate (Ex. 28) and 3.73 grams of diethylphosphite in 30 cc of ether was treated with 2.73 grams of triethylamine. The ethereal solution was extracted several times with water. After the ethereal solution was dried over anhydrous magne 0,0'- Diisopropy l-S-( 2-Neopentyl-4,4-.dimethyl-3- thione-pentene-l monothiophosphate In a fashion as described in Example 3C, there was reacted 6.0 grams of 3-tertiary b'utyl-4-neopentyl-1,2

dithiolium perchlorate (Ex. 2B), 4.49 grams of diisopropyl phosphite and 2.73 grams of triethylamine. The reaction mixture was worked up in a manner as described in Example 3C to yield 7.1 grams of theory) of 0,0-diisopropyl-S-(2-neopentyl-4,4-dimethyl- 3-thione-pentene-l) monothiophosphate as a purple liquid; n.m.r. (solvent CCl 'r in ppm, 4.00, 1 H doublet (J 10 cps, vinyl); 5.30, 2 H multiplet (isopropoxy); 7.60, 2 H singlet (neopentyl); 8.59, 9 H singlet (tcrtiarybutyl); 8.67, 12 H doublet (isopropoxy); and 9.03, 9 H singlet (tertiarybutyl). Anal. Calculated for c H O PS z P, 7.90 Found:

EXAMPLE 5c 0,0-Di-n-butyl-S-(2-Neopentyl-4,4-dimethyl-3- thione-pentene-l) monot hiophosphate As described in Example 3C, ther" was reacted 6.0 grams of 3-tertiarybutyl-4-neope1 'l-1,2-dithiolium perchlorate (Ex. 28), 5.24 grams or di-n-butyl phosphite and 2.73 grams of triethylamine. Therewas isolated 7.6 grams 100% of theory) of 0,0-di-n-butyl-S- (2-neopentyl-4,4-'dimethyl-3-thione-pentene-l) monothiophosphate as a purple liquid; n.m.r. (solvent CCl 'r in ppm, 4.03, 1 H doublet (J 10 cps, vinyl); 5.92, 4 H multiplet (n-butyl); 7.62, 2 H singlet (neopentyl); 8.12 930,14 H multiplet (n-butyl);"8.59 9 H singlet (tertiarybutyl); and 9.05, 9 H singlet (t-butyl).

. EXAMPLE 6C 0,0-l)iphcnyl-S-(2-Neopentyl-4,4-dimethyl-3-thionepentenc-l monothiophosphate To a mixture of 10.0 grams of 3-tertiarybutyl-4- neopentyl- 1,2-dithiolium hydrogen sulfate (Ex. 1A)

and 4.7 grams of diphenyl phosphite in 30 cc of ether was added 2.0 grams oftriethylamine. The mixture was stirred for minutes andfiltered. The ether was dis- I EXAMPLE 7C 3 -tertiarybutyl-4-Neopentyl-1,2-Dithiolium Perchlorate A sampleof 1.5 grams of 0,0'-dimethyl-S-(2- neopentyl-4,4-dimethyl-3-thione-pentene-1 monothiophosphate was dissolved in grams of methanol. To

the solution was added 2.3 grams of- 70% perchloric acid and 45 grams of water. The precipitate was filtered off and dried. The product was in all respects identical to 3-tertiarybutyl-4-neopentyl-1,2 dithiolium perchlorate as described in Ex. 2B.

The corresponding product was obtained by treating 0,0-diethyl-S-(2-neopentyl-4,4-dimethyl-3-thionepentene-l) monothiophosphate with 70% perchloric acid.

EXAMPLE 8C A sample of 0.6 grams of 0,0-diphenyl-S-(2- neopentyl-4,4-dimethyl'-3-thione-pentene-l) monothiophosphate dissolved in 19 grams of methanol was treated with 0.9 grams of 70% perchloric acid. To the mixture was added 18 grams of water. The precipitate was filtered offand dried. There was isolated 0.6 grams of the corresponding dithiolium compound of Ex. 28.

The formulae of the monothiophosphate formed in the above examples are in the following Table.

Ex. R R R, R,v

1C tert-Butyl Neopentyl H CH 2C tert-Butyl Neopentyl H CH, 3C tert-Butyl Neopentyl H Cg; 4C tert-Butyl Neopentyl H lSOCaHy 5C tert-Butyl Neopentyl H n-C H, 6C Neopentyl H Phenyl tert-Butyl Other monothiophosphates similarly prepared are presented in the following Table.

Table IV Ex. dithiolium starting No. material phosphite Product 9c 3,5 Diphenyl 1,2- dimethyl' 0,0-Diniethyl-S- dithiolium perphosphite (1,3 diphenyl-S-thionechlorate propene-l) monothio 1 phosphate 10C 3,5 Diphenyl 1,2 diphenyl 0,0-Diphenyl-S- (1,3

dithiolium perphosphite diphenyl-3-thionechlorate propene-l) monothiophosphate 11C 3-Phenyl-4-methyl dimethyl '0,0'-Dimethyl-S -(2- 1,2-dithiolium methyl-3-phenyl-3- phosphite perchlorate thione-propene-l) monothiophosph ate Since the. thiophosphates of this invention are more soluble in organic systems than the corresponding dithioliumcompounds, they can be added to the organic phase of the systems in greater concentrations than the dithiolium compounds. When the organic phase is brought into contact with the acidic aqueous phase, the thiophosphate is converted to the dithiolium compound at the interphase and extracted into the aqueous phase in which it is more soluble. In this way there is a gradual and-continuous transfer from one phase to another as it is converted to its anti-corrosive form. Thus, the oil solubility of the thiophosphate facilitates handling in oil systems and acid convertibility with subsequent enhanced water solubility of the product transports the corrosion inhibitor to the aqueous phase. [n this way the corrosion inhibitor is stored in the organic phase until ready for use where it gradually migrates to the aqueous acidic corrosive system as required.-

ln addition, an organic solution or suspension of the thiophosphate can be placed in contact with the metal, as a liquid, grease, etc., and as acid fumes or aqueous acid vapors contact the system, the thiophosphate converts to thedithiolium compound which acts as a corrosion inhibitor as required.

USE IN FLUIDS FOR DRILLING WELLS This phase of the invention relates to the use of the compounds of this invention as corrosion inhibitors in producing an improved drilling fluid useful in drilling oil and gas wells.

Fluids commonly used for the drilling of oil and gas wells are .of two general types: water-base drilling fluids comprising, for example, a clay suspended in water, and oil-base drilling fluids comprising, for example, a clay or calcium carbonate suspended in mineral oil.

A third type of drilling fluid which has recently been developed is one of oil-in-water or water-in-oil emulsion, for example, emulsions of mineral oil in water or water in mineral oil formed by means of emulsifiers such as sulfuric acid; Turkey-red oil; soaps of fatty acids, for example, sodium oleate; emulsoid colloids, for example, starch, sodium alginate, etc. Varying amounts of finely divided clay, silica, calcium carbonate, blown asphalt and other materials may be added to these emulsions to improve their properties and control their weight.

l have now discovered that the compositions of this invention can be employed as a corrosion inhibitor in drilling fluids.

USE IN AIR DRILLING It has long been conventional practice in drilling deep bore holes to circulate a drilling mud down through the drill stem and up through the bore hole between the wall of the bore hole and the drill stem for the removal of chips or cuttings from the bore hole and to provide support for the wall of the bore hole. More recently, in the drilling of holes in which wall support provided by drilling mud is .not employed, drilling has been carried out with the use of air for chip removal. Such drilling is not only normally faster than mud drilling, but is indispensable in areas where the supply of water is limited or when drilling through cavernous formations into which the drilling mud flows and becomes lost.

The increasing popularity of air or gas drilling has come about not only because this method of drilling is frequently faster, as noted above, but for the additional reasons that the drill bits last' longer, the provision and handling of water under wide ranges of temperature conditions is avoided, boring samples are easily observed when they are not mixed with mud, and there is no loss involved as in the case of mud drilling when drilling through cavernous formations. prompt removal of water entering the hole maintains a dry hole and the likelihood of wall collapse is thereby reduced.

In a typical air drilling operation there may be provided, for example, an up-flow of air in the bore hole having a velocity of the order of 3,000 feet per minute. This flow of air upwardly through the bore hole, which is produced by air pumped downwardly through the drill stem, provides adequate removal of cuttings. The air is delivered to the drill stem at pressures of 20 to 60 lbs. per square inch and for dewatering or for breaking obstructions, as will be hereinafter described, the pressures may be increased to 180 to 200 lbs. or more per square inch.

Furthermore,

Air drilling operations are frequently hampered by the inflow of water into the bore hole when the drill bit is penetrating a water bearing stratum or when the bore hole has passed through a water bearing stratum that has not been cased. Normally, if drilling proceeds uninterruptedly both before and during penetration into a water bearing stratum, the flow of air is sufficient to blow the water out of the bore hole along with the cuttings and drilling dirt. There are, however, two major problems encountered in air drilling when water is entering the bore hole. The first problem occurs when there is a small inflow of water sufficient to cause a dampening of the cuttings which, under certain conditions, will then ball-up, clogging and sometimes jamming the drill bit. The second problem is encountered when there is a substantial amount of water remaining in the bottom of the bore hole during drilling causing a sloughing of the side wall of the bore hole. This latter condition may arise even though the water entering the bore hole is being blown out of the hole as fast as it enters. If there is a substantial inflow of water or if there is a substantial flow of water past a region of the bore hole susceptible to this condition, the water passing that region of the bore hol'e may cause a sloughing of the side wall.

The addition of foam forming materials to the air flow when air drilling is employed in conjunction with,

sufflcient water to provide foaming gives rise to numerous advantages in drilling operations. The water may be introduced either through a water bearing stratum being penetrated by the drill bit or, alternatively, if the hole is dry, water may be introduced from the surface of the earth through the drill stem in conjunction with the delivery of compressed air and foam forming material through the drill stem to the drill bit. In either case the water may be said to be existingin the bore hole, and drilling operations are described in U.S.P. 3,130,798.

The amount of the compositions of the invention to be employed as a corrosion inhibitor can vary widely depending upon particular compounds, the particular system, the amounts of oxygen present, etc. I may employ concentrations of from about 0.5 to 5,000 p.p.m., such as from about 4 to 4,000 p.p.m., for example from about 20 to 2,000 p.p.m., but preferably from about to 1,000 p.p.m. The optimum amount, to be determined in each instance, which will depend on function and economics, can be lesser or greater than the above amounts under proper conditions.

USE IN BRINES This phase of the invention relates to the prevention of corrosion in systems containing a corrosive aqueous medium, and most particularly in systems containing brines.

More particularly, this invention relates to the prevention of corrosion in the secondary recovery of petroleum by water flooding and in the disposal of waste water and brine from oil and gas wells. Still more particularly, this invention relates to a process of preventing corrosion in water flooding and in the disposal of waste water and brine from oil'and gas wells which is characterized by injecting into an underground formation an aqueous solution containing minor amounts of compositions of this invention, in sufficient amounts to prevent the corrosion of metals employed in such operation. This invention also relates to corrosion inhibited brine solutions of these compounds.

When an oil well ceases to flow by the natural pressure in the formation and/or substantial quantities of oil can no longer be obtained by the usual pumping methods, various processes are sometimes used for the treatment of the oil-bearing formation in order to increase.

' formation, are pumped out of an adjacent well usually referred to as .a producing well. The oil which is pumped from the producing well is then separated from the water that has been pumped from the producing well and the water-is pumped to a storage reservoir from which it can again be pumped into the injection well. Supplementary water from other sources may also be used in conjunction with the produced water. When the storagereservoir is open to the atmosphere and the I oil is subject to aeration this type of waterflooding system is referred to herein as an open water flooding system. v v

1 Because of the corrosive nature of oil field brines, to economically produce oil by-water flooding, it is necessary to prevent or reduce corrosion sincecorrosion increases the cost thereof by making it necessary to repair and replace such equipment at frequent intervals.

' l have now discovered a method of preventing corrosion in systems containing a corrosive aqueous media, and most particularly in systems containing brines, which is characterized by employing the compositions of this invention.

I have also discovered an improved process of protecting from corrosion metallic equipment employed in secondaryoil recovery by water flooding such as injection wells, transmission lines, filters, meters, storage tanks, and other metallic implements employed therein and particularly those containing iron, steel, and ferrous alloys, such process being characterized by emeconomical method of solving the corrosion problems encountered in disposing of unwanted water.

Water flood and waste disposal operations are too well known to require further elaboration. In essence, in the present process, the flooding operation is effected in the conventional manner except that the preferably about 15 to 1,500 ppm. The upper limiting amount of the compounds is determined by economic considerations. Since the success of a water flooding operation manifestly depends upon its total cost being less than the value of the additional oil recovered from the oil reservoir, it is quite important to use as little as possible of these compounds consistent with optimum corrosion inhibition. Optimum performance is generally obtained employing about 1,000 ppm. Since these compounds are themselves inexpensive and are used in low concentrations, they enhance the success of aflood operation by lowering the cost thereof.

In addition, these compounds are not sensitive to oxygen content of the water and these are effective corroploying in water flood operation the compositions of I this invention. I

This phase of the invention then is particularly concerned with preventing corrosion in a water flooding process characterized by the flooding medium containing an aqueous or an oil field brine solution of these compounds.

In many oil fields large volumes of water' are produced and must be disposed of where water flooding operations are not in use or where water flooding operations cannot handle the amount of produced water. Most states have laws restricting pollution of streams and land with'produced waters, and oil producers must then find some method of disposing of the waste produced saltwater. In many instances, therefore, the salt water is disposed of by injecting the water into permeable low pressure strata below the fresh water level. The formation into which the water is injected is not the oil producing formation and this type of disposal is defined as salt water disposal or waste water disposal. The problems of corrosion of equipment are analogous to those encountered in the secondary operation by water flooding.

The compositions of this invention can also be used in such water disposal wells thus providing a simple and sion inhibitors'in both openwater flooding systems and closed water flooding systems.

v While the flooding mediumemployed in accordance with the present invention contains water or oil field brine and the-compounds, the medium may also contain other materials. For example, the flooding medium may also contain other agents such as surface active agents or detergents which aid in wetting throughout the system and also promote the desorption of residual oil from the formation, sequestering agents which prevent the deposition of calcium and/or magnesium compounds in the-interstices of the formation, bactericides which prevent the formation from becoming plugged through bacterial growth, tracers, etc. Similarly, they may be employed in conjunction with any of the operating techniques commonly employed in water flooding and water disposal processes, for example five spot flooding, peripheral flooding, etc., and in conjunction with other secondary recovery methods.

USE IN ACID SYSTEMS USE AS PICKLING INHIBITORS This phase of the invention relates to pickling. More particularly, the invention is directed to a pickling composition and to a method of pickling ferrous metal. The

term ferrous metal as used herein refers to iron, iron alloys and steel.

To prepare ferrous metal sheet, strip, etc., for subsequent processing, it is frequently desirable to remove oxide coating, formed during manufacturing, from the surface. The presence of oxide coating, referred to as scale is objectionable when the material is to undergo subsequent processing. Thus, for example, oxide scale must be removed and a clean surface provided if satisfactory results are to be obtained from hot rolled sheet and strip in any operation involving deformation of the product. Similarly, steel prepared for drawing work.

The chemical process used to remove oxide from metal surfaces is referred to as pickling. Typical processes involve the use of aqueous acid solutions, usually inorganic acids, into which the metal article is immersed. The acid solution reacts with the oxides to form waterand a salt of the acid. A common problem in this process is overpickling which is a condition resulting when the ferrous metal remains in the pickling solution after theoxide scale is removed from the surface and the pickling solution reacts with the ferrous base metal. An additional difficulty in pickling results from the liberated'hydrogen being absorbed by the base metal. and causing hydrogen embrittlement. To overcome the aforementioned problems in pickling, it has been customary to add corrosion inhibitors to the pickling solution.

The present invention avoids the above-described problems in pickling ferrous metal articles and provides a pickling composition which minimizes corrosion, overpickling-and hydrogen embrittlement. Thus the pickling inhibitors described herein not only prevent excessive dissolution of the ferrous base metal but'effectively limit the amount of hydrogen absoprtion thereby during pickling. According to the invention, a pickling composition for ferrous metal is provided which comprises a pickling acid such as sulfuric or hydrochloric acid and a small but effective amount of the dithiol thione compound of this invention, for example at least about '5 p.p.m., such as from about 100 to 5,000 p.p.m., but preferably from about 500 to 1,500 p.p.m.

' Ferrous metal articles are pickled by contacting the surface (usually by immersion in the pickling solution) with a pickling composition as described to remove oxide from their surface with minimum dissolution and hydrogen embrittlement thereof and then washing the ferrous metal to remove the pickling composition therefrom.

USE IN ACIDIZING EARTH FORMATIONS The compositions of this invention can also be used as corrosion inhibitors in acidizing media employed in the treatment'of deep wells to reverse the production of petroleum or gas therefrom and more particularly to an improved method of acidizing a calcareous or magnesium oil-bearing formation.

It is well known that production of petroleum or gas from a limestone, dolomite, or other calcareousmagnesium formation can be stimulated by introducing an acid into the producing well and forcing it into the oil or gas bearing formation. The treating acid, commonly a mineral acid such as HCl, is capable of forming water soluble salts upon contact with the formation and is effective to increase the permeability thereof and augment the flow of petroleum to the producing well.

The corrosion inhibitors were evaluated using sand blasted 1,020 mild steel coupons monitored by a polarization resistance meter, a Pair instrument described in U.S. Pat. No. 3,406,101. i

The acid was placed in a beaker and the coupons placed in the acid. Corrosion rates were measured at various time intervals and percent protection calculated in the usual manner as follows:

Percent protection (R R )/R X 100 where R is corrosion rate without inhibitor R is corrision in presence of inhibitor.

The utility of the compositions of this invention is illustrated in the following Table.

USE AS CORROSION INHIBITORS IN HIGHLY ACID SYSTEMS Table V H 180 g per lit-er Fe as FeSO, 10 g per liter Fe as Fe(SO 10 g per liter Inhibitor concentration 1,000 p.p.m.

Product of protection An important aspect of pickling inhibitors is that they should remain effective in presence of dissolved ferrous ions (from dissolution of the oxide scale). The continued effectiveness of the present compositions is illustrated in the above table.

The compositions of this invention may also be added to other aqueous and/or oxygenated systems such as steam generating systems, water circulating systems such as in cooling towers, in automobile radiators, in diesel locomotive engines, in boiler water, seawater ship ballast, etc.

The term dithiolium compounds" includes 1,2- dithiolium compounds and derivatives thereof such as salts, quaternaries, etc.

The amount of thiophosphateemployed in treating the corrosive systems of this invention will vary with the particular compound employed, the particular system, the solids present in the system, the degree of corrosivity of the system, etc. A minor amount of the compound is generally employed sufficient to impart corrosion protection to the system. In general one employs concentration of trace amounts such as from about 1.0 p.p.m. to 10,000 p.p.m., for example from 5 to 5,000 p.p.m., such ast'rom to 2,500 p.p.m., but preferably from 500 to 2,000 ppm. In practice, concentrations of 1,000 2,000 ppm, are employed.

As is quite evident, new thiophosphates of this invention will beconstantly developed which could be useful in this invention. It is, therefore, not only impossible to attempt a comprehensive catalogue of such compositions, but to attempt to describe the invention in its broader aspects in terms of specific chemical names used would be too voluminous and unnecessary since one skilled in the art could by following the description of the invention herein select a useful dithiolethione compound. This invention lies in the use of suitable thiophosphates asrcorrosion inhibitors inaqueous and- /or oxygenated and/or acid systems and their individual compositions are important only in the sense that their properties can affect this function. To precisely define each specific useful thiophosphate and aqueous system in light of the present disclosure would merely call for knowledge within the skill of the art in a manner analogous to a mechanical engineer who prescribes in the construction of a machine the proper materials and the proper dimensions thereof. From the description in this specification and with. the knowledge of a chemist, one will know or deduce with confidence the applicability of specific thiophosphates suitable for this invention by applying them in the process set forth herein. In-analogy to the case of a machine, wherein the use of certain materials of construction or dimensionsof part would lead to no practical useful result, various materials will be rejected as inapplicable where others would be operative. I can obviously assume that no one will wish to use a useless thiophosphate nor will be misled because of the Where X is O or S, R is a hydrocarbon radical and R is a 3-thione-propene-l group or substituted derivative thereof which comprises reacting a dithiolium compound with a phosphite ester under basic conditions.

2. The process of preparingthethiophosphates of claim 1 where R is alkyl or aryl and the substitution on the 3-thione-propene-l group is a hydrocarbon radical.

3. The process of preparing the thiophosphates of claim 2 where the thiophosphate is a monothiophosphate and where R is lower alkyl, phenyl or a substituted phenyl group and. the substituted 3-thionepentene-l group is 2 neopentyl- 4,4-dimethyl-3-thionepentene-l.

4. The process of preparing the monothiophosphate of claim 3 where R is methyl, ethyl, propyl or n-butyl. 

1. THE PROCESS OF PREPARING THIOPHOSPHATES OF THE FORMULA
 2. The process of preparing the thiophosphates of claim 1 where R is alkyl or aryl and the substitution on the 3-thione-propene-1 group is a hydrocarbon radical.
 3. The process of preparing the thiophosphates of claim 2 where the thiophosphate is a monothiophosphate and where R is lower alkyl, phenyl or a substituted phenyl group and the substituted 3-thione-pentene-1 group is 2 neopentyl-4,4-dimethyl-3-thione-pentene-1.
 4. The process of preparing the monothiophosphate of claim 3 where R is methyl, ethyl, propyl or n-butyl. 